Server Side Includes
Server side includes are allowed with the exception of Exec which is disallowed. Although it is slightly more work (you have to spit out a header), just about anything you could do with Exec can be done with a CGI script. The reason Exec is disallowed is that, unlike CGI scripts, it is not restricted to one directory and thus it is easy to accidentally execute the wrong thing with unknown and possibly nasty consequences. Also, CGI and PHP is executed with your user ID, there is no method of doing that with SSI.
Normally, “.html” files are not parsed for SSI directives. There are two ways to tell the server to parse a file for SSI directives. If you give the file an extension of “.shtml” the server will parse the file for SSI directives. Also, if you set the user execute bit the file will be parsed for SSI directives. This is known as the Apache X-bit hack, although today it is a standard feature. To do this type:
chmod u+x file.html
The include syntax to use inside an HTML file to include another file is:
<!--#include file="included.html" -->
Cache control is no longer done with the group execute bit. This must now be done with a “.htaccess” file. This method is far more flexible in that not only can you specify what and what not to cache, but you can specify how long to cache it and with what criteria. See http://httpd.apache.org/docs/current/mod/mod_expires.html for details.